The application discloses subject matter related to that disclosed and claimed in the patent application Ser. No. 51,473, filed June 25, 1979 entitled "Microprocessor Based Computer Terminal" and patent application Ser. No. 51,783, filed June 25, 1979 entitled "Low Cost Digital Data Display Apparatus".
The invention relates generally to the field of digital computer peripherals and more particularly to the field of programmable computer terminals. Prior art terminals utilized expensive cathode ray tubes and special interface chips such as USARTS to accomplish the task of communicating with and displaying information from the main computer. The cheapest terminals available in 1979 were around 500 dollars and not as powerful or flexible as the disclosed terminal.
The hardware disclosed herein is capable of reading and writing on a serial communication line at adjustable speeds up to 600 baud utilizing a modem. It can read a keyboard and read and write from a parallel port. All entering data from any input may be displayed on a black and white television set and all data being displayed may simultaneously be transmitted out the serial or parallel ports. Upper and lower case and page and scroll mode are available and any combination of inputs and outputs can be set from the keyboard. Field reversal is also available. Carriage return, line feed, clear screen, home up and cursor positioning are also available. Finally, a limited graphics capability exists by virtue of a PROM that may be programmed with any graphics patterns desired by an individual user.
The numerous functions and flexibility provided in the disclosed apparatus is due to use of a programmed microprocessor. The low cost is attributed primarily to use of a standard home television set in conjunction with a microprocessor programmed to perform many of the functions formerly performed by separate chips.
The prior art is crowded with computer terminal apparatus. However, the least expensive computer terminal available at the time of filing sold for more than twice as much as the disclosed computer terminal could be built for in kit form. Further, no terminal in the prior art had as many options and capabilities and yet had as low a cost as the disclosed terminal.